1. Field of the Invention
The present invention relates to a heat exchanger in which different core portions are integrated with each other, and more particularly the present invention can be effectively applied to an integration of a radiator of an engine which is a driving source of a vehicle and a condenser of an automotive air conditioning apparatus.
2. Description of Related Art
Conventionally, an automotive air conditioning apparatus is assembled into a vehicle in a car dealer or the like after the vehicle has been completed. Recently, however, the automotive air conditioning apparatus is generally installed in the vehicle when the vehicle is completed, and therefore the automotive air conditioning apparatus is assembled with automotive parts in the assembling steps of the vehicle at the manufacturing plant.
There have been proposed a plurality of heat exchangers in which different core portions such as a radiator and a condenser are integrated. By integrating the radiator which is an automotive part and the condenser which is an automotive air conditioning apparatus part with each other, the heat exchanger is downsized and the assembling steps can be decreased.
However, because the different core parts are integrated with each other, heat transmission is generated through the integrated part so that there is a problem in that the heat exchange efficiency of the core portion to which heat is transmitted is decreased. That is, when the radiator and the condenser are integrated with each other, heat is transmitted from the radiator to the condenser so that the heat exchange efficiency of the condenser is decreased.
To suppress the heat transmitting amount, as disclosed in JP-A-3-177795, for example, cooling fins of first core portion and second core portion are integrated with each other, and a slit shaped recess portion is formed in a zigzag shape in a height direction of the integrated cooling, and a heat transmitting passage for transmitting heat is meanderingly formed so as to prolong the heat transmitting passage.
In the above-described heat exchanger, the heat transmitting passage is prolonged so that heat transmitted from the radiator to the condenser is suppressed, however, the heat transmission cannot be interrupted completely. Thus, to maintain a desired heat exchange amount in the condenser core portion, it is necessary to decide the capacity of the condenser core portion by considering the decrease of the heat exchange efficiency.
That is, when designing a heat exchanger in which different core portions are integrated with each other, it is necessary for a core portion to which heat is transmitted (condenser core portion) to be made larger by considering the decrease of the heat exchange efficiency in the core portion to which the heat is transmitted (condenser core portion).
However, if only the heat transmitting passage is simply made larger, the principal object for a small-sized heat exchanger in which different core portions are integrated with each other cannot be achieved.